Chromatographic and Voltammetric Characterization of Chlorogenic Acids in Coffee Samples

Ivana Tomac,Lidija Jakobek,Marijan Šeruga

doi:10.5562/cca3439

Abstract

The accurate and precise characterization of eight chlorogenic acids (CGAs) isomers, caffeoylquinic acids (5-CQA, 4-CQA, 3-CQA), dicaffeoylquinic acids (3, 5-diCQA, 4, 5-diCQA, 3, 4-diCQA), and feruloylquinic acids (5-FQA, 4- FQA), was carried out using different brands of coffee. High-performance liquid chromatography (HPLC), differential pulse (DPV) and square- wave voltammetry (SWV) were applied for the investigation. HPLC proved to be an accurate and precise method for separation, identification and quantification of CGAs isomers in coffee extracts. DPV and SWV have shown that electrochemical behaviour of coffee extracts was very similar to that of CGAs isomers and DPV and SWV can be used for the correct characterization of CGAs in coffee. All three techniques have shown a very high correlation of CGAs content in all investigated coffee samples. Therefore, HPLC, DPV and SWV methods can be used in combination as very selective, sensitive and precise methods for characterization of CGAs isomers in coffee extracts.

Highlights

C OFFEA arabica and Coffea robusta from the family Rubiaceae are the most important types of coffee beans.[1]
The reason is that the retention times of both diCQAs were very close and the individual peaks were thereby connected in one common peak in all analysed coffee extracts (Figures 1, 2)
In order to confirm the identification of the oxidation peaks, spiking of all coffee extracts was performed by adding the known concentration of each individual CQAs, diCQAs and FQAs

Summary

Introduction

C OFFEA arabica and Coffea robusta from the family Rubiaceae are the most important types of coffee beans.[1]. There is a need for an efficient separation, identification and quantification of each individual chlorogenic acids isomers (CQAs, diCQAs and FQAs) in coffee, using HPLC/PDA technique and that was one of the aims of this study. HPLC/PDA method was performed to acquire the retention times and UV-Vis spectra of each individual CGAs. This technique allowed the identification and quantification of every single standard in the coffee extracts.

Results

Conclusion